Structure and physicomechanical properties of NbN-based protective nanocomposite coatings: A review

This review summarizes the present-day achievements in the study of the structure and properties of protective nanocomposite coatings based on NbN, NbAlN, and NbSiN prepared by a variety of modern deposition techniques. It is shown that a change in deposition parameters has a significant effect on the phase composition of the coatings. Depending on the magnitude of negative potential on the substrate, the pressure of nitrogen or a nitrogen-argon mixture in the chamber, and the substrate temperature, it is possible to obtain coatings containing different phases, such as NbN and SiN (x) (Si3N4), AlN, and NbAl2N. It is found that, in the case of formation of the epsilon-NbN phase, the coatings become very hard; their hardness achieves values on the order of 53 GPa. At the same time, they remain thermally stable at temperatures of up to 600A degrees C, chemically inert, and resistant to wear. The effect of the nanograin size, the volume fraction of boundaries and interfaces, and the point defect concentration on the physicomechanical properties of these coatings is described. Niobium nitride-based coatings can be used in superconducting systems and single-photon detectors; they are capable of operating under the action of strong magnetic fields of up to 20 T; they can be used in integrated logic circuits and applied as protective coatings of machine parts, edges of cutting tools, etc.